/* ===========================================================
 * AFreeChart : a free chart library for Android(tm) platform.
 *              (based on JFreeChart and JCommon)
 * ===========================================================
 *
 * (C) Copyright 2010, by ICOMSYSTECH Co.,Ltd.
 * (C) Copyright 2000-2008, by Object Refinery Limited and Contributors.
 *
 * Project Info:
 *    AFreeChart: http://code.google.com/p/afreechart/
 *    JFreeChart: http://www.jfree.org/jfreechart/index.html
 *    JCommon   : http://www.jfree.org/jcommon/index.html
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * [Android is a trademark of Google Inc.]
 *
 * ----------------
 * KeyedValues.java
 * ----------------
 * 
 * (C) Copyright 2010, by ICOMSYSTECH Co.,Ltd.
 *
 * Original Author:  shiraki  (for ICOMSYSTECH Co.,Ltd);
 * Contributor(s):   Sato Yoshiaki ;
 *                   Niwano Masayoshi;
 *
 * Changes (from 19-Nov-2010)
 * --------------------------
 * 19-Nov-2010 : port JFreeChart 1.0.13 to Android as "AFreeChart"
 * 
 * ------------- JFreeChart ---------------------------------------------
 * (C) Copyright 2002-2008, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * Changes:
 * --------
 * 23-Oct-2002 : Version 1 (DG);
 * 12-Jan-2005 : Updated Javadocs to specify new behaviour when key
 *               is not recognised (DG);
 * ------------- JFREECHART 1.0.0 ---------------------------------------------
 * 02-May-2006 : Updated API docs (DG);
 *
 */

package org.afree.data;

import java.util.List;

/**
 * An ordered list of (key, value) items where the keys are unique and non-
 * <code>null</code>.
 * 
 * @see Values
 * @see DefaultKeyedValues
 */
public interface KeyedValues extends Values {

    /**
     * Returns the key associated with the item at a given position. Note that
     * some implementations allow re-ordering of the data items, so the result
     * may be transient.
     * 
     * @param index
     *            the item index (in the range <code>0</code> to
     *            <code>getItemCount() - 1</code>).
     * 
     * @return The key (never <code>null</code>).
     * 
     * @throws IndexOutOfBoundsException
     *             if <code>index</code> is not in the specified range.
     */
    public Comparable getKey(int index);

    /**
     * Returns the index for a given key.
     * 
     * @param key
     *            the key (<code>null</code> not permitted).
     * 
     * @return The index, or <code>-1</code> if the key is unrecognised.
     * 
     * @throws IllegalArgumentException
     *             if <code>key</code> is <code>null</code>.
     */
    public int getIndex(Comparable key);

    /**
     * Returns the keys for the values in the collection. Note that you can
     * access the values in this collection by key or by index. For this reason,
     * the key order is important - this method should return the keys in order.
     * The returned list may be unmodifiable.
     * 
     * @return The keys (never <code>null</code>).
     */
    public List getKeys();

    /**
     * Returns the value for a given key.
     * 
     * @param key
     *            the key.
     * 
     * @return The value (possibly <code>null</code>).
     * 
     * @throws UnknownKeyException
     *             if the key is not recognised.
     */
    public Number getValue(Comparable key);

}
